Minor: Additional functions (#25)

* several functions. fixes #1 and #2

* multi selection functionality

core/include/ccm/util/CardLookupDetect.hpp

@@ -0,0 +1,24 @@
+#pragma once
+
+// Shared rule for bidirectional Set # Auto detect (name ↔ set number):
+// when both fields are filled, the field the user last edited is the lookup key.
+
+namespace ccm {
+
+enum class CardLookupEditField { None, Name, SetNo };
+
+// Returns true when Auto detect should run setNo → name (reverse).
+// `nameEmpty` / `setNoEmpty` are already trimmed/normalized by the caller.
+// When both are empty the result is false (caller shows a validation message).
+// When only one is filled, that direction wins. When both are filled, SetNo
+// wins only if it was the last edited lookup field; otherwise Name wins
+// (including `None`, matching the historical default).
+[[nodiscard]] inline bool preferDetectBySetNo(bool nameEmpty,
+                                              bool setNoEmpty,
+                                              CardLookupEditField lastEdited) noexcept {
+    if (nameEmpty) return !setNoEmpty;
+    if (setNoEmpty) return false;
+    return lastEdited == CardLookupEditField::SetNo;
+}
+
+}  // namespace ccm